| 摘要(英) |
In the engineering of rock masses, such as tunnels, rock slopes, and foundation construction within fractured rock formations, discontinuity is a crucial factor influencing the behavior of the engineering structures. This influence is not only related to the orientation of the discontinuities but also closely tied to factors such as the excavation direction of tunnels, the slope of rock, and the orientation of foundation configurations. Despite the acknowledgment by previous engineers of the anisotropic behavior in rock engineering and the widespread application of empirical rules in practical projects, the lack of rigorous and comprehensive results from physical model tests, analytical analyses, or numerical analyses regarding anisotropic behavior in rock engineering has led to a long-standing deficiency in verifying the accuracy of empirical rules.
This paper aims to explore the anisotropic behavior of rock tunnels, focusing not only on validating the rationality of adjusting orientation scores in Rock Mass Rating (RMR) and Rock Structure Rating (RSR) but also emphasizing the data processing and interpretation of numerical analyses of three-dimensional synthetic rock mass tunnel models. Two-dimensional numerical simulation tools can not address the effects of different excavation directions, so this paper utilizes three-dimensional numerical simulation programs PFC3D and RS3 to investigate the influence of tunnel excavation direction on the stability of fractured rock masses. The verification of tunnel excavation using the Kirsch equations confirms that both PFC3D and RS3 are suitable for simulating tunnel excavation in fractured rock masses. A Bonded Particle Model (BPM) combined with a Discrete Fracture Network (DFN) is generated using PFC3D to construct synthetic rock mass tunnel models with a set of discontinuities. The dip angle (?j) variables include: ?j=0˚, 15˚, 30˚, 45˚, 60˚, 75˚, and 90˚. Three tunnel excavation scenarios are simulated: Scenario 1 (γ=90˚): Strike parallel to the excavation direction; Scenario 2 (γ=0˚): Strike perpendicular to the tunnel axis and direction of drive with dip; Scenario 3 (γ=180˚): Strike perpendicular to the tunnel axis and direction of drive against dip. RS3 also performs simulations with the same variables and scenarios. Through numerical simulation results, the paper investigates the influence of various variables on tunnel stability, and quantitative indicators such as displacement fields, radial displacements, strain invariants, strain energy, and potential energy are used to describe tunnel stability. By comparing simulation results with existing literature, the paper consolidates a scoring adjustment system for discontinuities concerning excavation direction and summarizes deformation patterns and distributions after tunnel excavation under various conditions.
The analysis of numerical results reveals that: (1) Displacement values around tunnels in RS3 are much smaller than those in PFC3D, especially when γ=0˚ and 180˚. RS3 shows extremely small displacement values around tunnels, with only slightly larger values when γ=90˚ and ?j=60˚ to 90˚, approximately 1/10 to 1/60 of the displacement values in PFC3D. (2) Theoretically, rock masses with a dip angle βj=90˚ should exhibit consistent stability when excavated in γ=0˚ and γ=180˚. However, RSR and RMR evaluations for excavations in γ=0˚ and 180˚ are "very favorable" and "fair," respectively, deviating from theoretical expectations. The analysis results for βj=45˚ and βj=90˚ in γ=90˚ and 180˚ show significant differences, indicating distinct tunnel behaviors, and suggesting that these should not be grouped under the same dip angle. Therefore, the dip angle grouping is refined from three groups to six groups, providing a more detailed scoring system and addressing the discrepancies in RSR and RMR evaluations. (3) Using strain invariants, strain deviator invariants, strain energy, radial displacement, and potential energy, the paper performs optimization fitting with RMR discontinuity orientation score adjustments. Radial displacement and potential energy show the highest correlation with RMR; out of 18 combinations, 10 are identical, while the remaining 4 differ by one grade and 4 differ by two to three grades. Strain invariants, strain deviator invariants, and strain energy are based on the assumption of small strains and must filter out particles with large displacements, making them unsuitable as indicators for tunnel stability. (4) Rock masses with high dip angles (βj=60˚~90˚), when excavated parallel to the discontinuity orientation (γ=90˚), exhibit significant differences in orientation score adjustments proposed by RS3 (finite element method) and PFC3D (discrete element method) compared to RMR. Reviewing previous research results, three main approaches are identified: finite element methods, discrete element methods, and model tests. Finite element methods (including RS3 in this paper) show similarities to RMR, while discrete element methods and model tests show similarities to PFC3D results. Finite element methods based on continuum mechanics may underestimate deformation significantly due to their inability to simulate large displacements associated with discontinuity sliding. This indicates that different numerical methods can lead to variations in analysis results. (5) Relative to radial displacement and potential energy, strain invariants, strain deviator invariants, and strain energy are not suitable as indicators of tunnel stability. However, each of these invariants and strain energy has different physical meanings. The first strain invariant (I1) represents volume strain in the rock mass around the tunnel; the second strain invariant (I2) and the second strain deviator invariant (J2) are suitable for describing shear failure due to discontinuity sliding; strain energy (U0) represents the product of stress and strain and is useful for marking the location of failure.(6) The investigation of tunnel stability requires careful consideration of data collection range, and this study adopts radial displacement measurements taken one and a half times the tunnel radius outward. The suitability of this approach is examined at distances of 2m, 6m, and 18m from the excavation face. When collecting data 2m ahead of the excavation face, the region near the excavation face exhibits greater stability when γ=90˚, while the region with lower inclination angles (γ=180˚) appears less stable. As the data collection range increases, the results show instability for γ=90˚, while the radial displacement for γ=0˚ and 180˚ tends to converge. This convergence suggests that the stability of these two angles should be similar after the tunnel is completely penetrated. Therefore, the study recommends analyzing the data up to half of the model′s excavation as a more suitable approach to distinguish and examine the stability behavior for γ=0˚ and 180˚. |
| 參考文獻 |
1. 田永銘、黃致維、黃森暉、裴文彬，（2021）「裂隙岩體隧道、岩坡與基礎之異向性工程行為」，科技部專題研究計畫期中進度報告，MOST 109-2221-E-008-015。
2. 任光正（2022），「裂隙岩體之基礎承載力異向性與變異性」，碩士論文，國立中央大學土木工程學系，中壢。
3. 李忠祐（2020），「運用數位影像法及羅吉斯迴歸探討鹼-骨材反應引致之裂縫行為」，碩士論文，國立中央大學土木工程學系，中壢。
4. 李惟誠（2018），「以數位影像法量測鹼-骨材反應引致之應變場與裂縫發展之關係」，碩士論文，國立中央大學土木工程學系，中壢。
5. 郭明傳（2005），「複合岩體之岩塊體積比量測及其力學行為」，博士論文，國立中央大學土木工程學系，中壢。
6. 黃致維（2020），「利用合成岩體模擬橫向等向性岩體之基礎承載力」，碩士論文，國立國立中央大學土木工程學系，桃園。
7. 黃森暉（2022），「從順向坡至逆向坡之崩塌行為模擬」，碩士論文，國立中央大學土木工程學系，中壢。
8. 裴文斌（2022），「Effect of Excavation Direction on Stability of Tunnels in Transversely Isotropic Rock Mass」，博士論文，國立中央大學土木工程學系，中壢。
9. 劉家豪（2019），「橫向等向性合成岩體之力學行為及其變異性」，碩士論文，國立中央大學土木工程學系，中壢。
10. 潘國樑（2007），「工程地質學導論」，科技圖書，第224頁。
11. 盧育辰（2009），「以UDEC模擬互層材料之力學行為」，碩士論文，國立中央大學土木工程學系，中壢。
12. Arai, N., and Chigira, M. (2019) “Distribution of gravitational slope deformation and deep-seated landslides controlled by thrust faults in the Shimanto accretionary complex,” Engineering Geology, Vol.260
13. Brown, E.T. (1981) “Rock Characterization Testing and monitoring: ISRM suggested methods,” Oxford, UK, pp. 211.
14. Bieniawski, Z.T. (1979) “The Geomechanics Classification in Rock Engineering Application,” Proceeding 4th International Congress on Rock Mechanics, Montreux, pp. 41-48.
15. Cai, H., Miyano, Y., and Nakada, M. (2009) “Long-term Open-hole Compression Strength of CFRP laminates based on Strain Invariant Failure Theory,” Journal of Thermoplastic Composite Materials, Vol. 22.
16. Cundall, P. A., and Strack, O. D. (1979) “A discrete numerical model for granular assemblies,” Géotechnique, Vol. 29, No. 1, pp. 47-65.
17. Damjanac, B., and Cundall, P.A. (2016) “Application of distinct element methods to simulation of hydraulic fracturing in naturally fractured reservoirs,” Computers and Geotechnics, Vol. 71, pp. 283-294.
18. Deere, D.U., and Miller, R.P. (1966) “Engineering classification and index properties for intact rock,” Air Force Laboratory Technical Report, No. AFNL-TR-65-116, Albuquerque, NM.
19. Dershowitz, W. and Herda, H. (1992) “Interpretation of fracture spacing and intensity,” in JR Tillerson and Wawersik, Proceedings of the 33rd U.S. Rock Mechanics Symposium, Balkema, Rotterdam, pp. 757–766.
20. Einstein, H.H., and Baecher, G.B. (1983) “Probabilistic and statistical methods in engineering geology,” Rock Mechanics and Rock Engineering, Vol. 16, No. 1, pp. 39-72.
21. Esmaieli, K., Hadjigeorgiou, J., and Grenon, M. (2010) “Estimating geometrical and mechanical rev based on synthetic rock mass models at Brunswick Mine,” International Journal of Rock Mechanics and Mining Sciences, Vol. 47, No. 6, pp. 915–926.
22. Fang, Q., Wang, G., Yu, F., Du, J. (2021) “Analytical algorithm for longitudinal deformation profile of a deep tunnel,” Journal of Rock Mechanics and Geotechnical Engineering, Vol. 13, pp. 845-854.
23. Gosse, J. and Christensen, S. (2001) “Strain Invariant Failure Criteria for Polymers in Composite Materials,” Collection of technical papers, 19th AIAA Applied Aerodynamics Conference and Exhibit, Vol. 1184.
24. Goyal, V., Garcia, C., Irizarry, E. (2016) “Micro Damage Initiation of Isotropic and Composites Structures Using Strain Invariant Failure Theory,” 57th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference.
25. Harman, A., Risborg, A., and Wang, C. H. (2008) “Experimental Testing of BMI Laminates With Stress Concentrations and the Evaluation of SIFT to Predict Failure,” Composite Structures, Vol. 86, pp. 85-95.
26. Horgan, C., Smayda, M. (2012) “The importance of the second strain invariant in the constitutive modeling of elastomers and soft biomaterials,” Mechanics of Materials, Vol. 51, pp. 43-52.
27. Itasca Consulting Group Inc. PFC3D (Particle Flow Code in 3 dimensions) (2019), Version 6.0, MN 55401.
28. McNaught, S. (2009) “Implementation Of The Strain Invariant Failure Theory For Failure Of Composite Materials,” Master′s thesis.
29. Naqvi M.W., Zaid, M., Sadique, R., and Alam M.M. (2017) “Dynamic analysis of rock tunnels considering joint dip angle : A finite element approach,”.
30. Potyondy, D.O., and Cundall, P.A. (2004) “A bonded-particle model for rock,” International Journal of Rock Mechanics and Mining Sciences, Vol. 41, No. 8, pp. 1329-1364.
31. Richards, R.J., (2000) “Principles of solid mechanics”, CRC Press, New York, pp. 23-61.
32. Romana, M. (1985) “New Adjustment Ratings for Application of Bieniawski Classification to Slopes,” Proceedings of the International Symposium on the Role of Rock Mechanics in Excavations for Mining and Civil Works, International Society of Rock Mechanics, Zacatecas, 49-53.
33. Romer, C., and Ferentinou, M. (2019) “Numerical investigations of Rock Bridge effect on open pit slope stability,” Journal of Rock Mechanics and Geotechnical Engineering, Vol. 11, No. 6, pp. 1184–1200.
34. Sagong, M., Park, D., Yoo, J., Lee, J. (2011) “Experimental and numerical analyses of an opening in a jointed rock mass under biaxial compression,” International Journal of Rock Mechanics and Mining Sciences, Vol. 48, pp. 1055-1067.
35. Scholtès, L., and Donzé, F.V. (2012) “Modelling progressive failure in fractured rock masses using a 3D discrete element method,” International Journal of Rock Mechanics and Mining Sciences, Vol. 52, pp. 18-30.
36. Tay, T. E., Tan, S. H. N., Tan, V. B. C., and Gosse, J. H. (2005) “Damage progression by the element-failure method (EFM) and strain invariant failure theory (SIFT),” Composites Science and Technology, Vol. 65, pp. 935-944.
37. Vaníček, P., Grafarend, E., Berber, M., (2008) “Short Note: Strain invariants,” Journal of Geodesy, Vol. 8, pp. 263 -268.
38. Wang, C., Tannant, D.D., and Lilly, P.A. (2003) “Numerical Analysis of the stability of heavily jointed rock slopes using PFC2D,” International Journal of Rock Mechanics and Mining Sciences, Vol. 40, No. 3, pp. 415–424.
39. Wang, L., Zhu, Z., Zhu, S., and Wu, J. (2023) “A Case Study on Tunnel Excavation Stability of Columnar Jointed Rock Masses with Different Dip Angles in the Baihetan Diversion Tunnel”.
40. Yang, X., Jing, H., Chen, K. (2016) “Numerical simulations of failure behavior around a circular opening in a non-persistently jointed rock mass under biaxial compression,” International Journal of Mining Science and Technology, Vol. 26, pp. 729-738.
41. Zhao, J., Zhoa, D., (2013) “Investigation of Strain Measurements using Digital Image Correlation with a Finite Element Method,” Journal of the Optical Society of Korea, Vol. 17, pp. 399-404. |
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